The bandwidth of Class A amplifiers is generally limited by parasitic capacitances which are associated with the internal components of the amplifier. This can be illustrated by reference to FIG. 1, which shows a circuit diagram of a conventional Class A amplifier 10. The input signal V.sub.IN is applied to the base of a transistor Q1. A resistor RE provides a conversion of input voltage to current, while a transistor Q2 acts as a common base or cascode amplifier stage to drive a load resistor RL. The base of cascode transistor Q2 is coupled to a reference voltage V.sub.b. Transistors Q3 and Q4 are emitter-followers which serve to isolate the impedance of resistor RL from the capacitance of the device driven by the amplifier, e.g., a cathode ray tube (CRT). Diodes D1 and D2 provide forward-bias to the output stage to reduce crossover distortion at low signal levels. The low frequency gain of the amplifier is approximately equal to RL/RE. The bandwidth of the amplifier is defined by the collector time constant formed by the load resistor RL and the parasitic capacitance associated with transistors Q2, Q3 and Q4 as well as stray capacitance associated with the circuit layout. These capacitances are represented collectively in FIG. 1 as C.sub.p1, C.sub.p2 and C.sub.p3.
A known technique used to increase the output power of power amplifiers is to connect a "bootstrap" capacitor between the output and the load resistor. This capacitor provides a source of base current to the emitter-follower (e.g., transistor Q4 in FIG. 1) when the amplifier is slewing in a positive direction. This increases the small-signal bandwidth of the output stage and makes the load resistor look more like a current source, thereby sharply increasing the slew rate.
Such a technique is not practical with a high-frequency amplifier fabricated on an integrated circuit (IC), because a relatively large capacitance would be required and this would significantly increase the size of the IC.